what to remember from a new study which points to immune dysregulation, and opens up avenues for screening and treatment

Researchers from Zurich (Switzerland) observed abnormalities in proteins involved in the immune reaction in the blood of patients.

Four years after its appearance, it is a pathology that remains poorly understood. Long Covid, which is estimated to affect around 10 to 20% of patients infected with Sars-CoV-2 according to the WHO, could be better diagnosed and treated thanks to the results of a team of researchers from the university and the Zurich hospital (Switzerland). In an article published in the journal Science, Friday January 19, they affirm that this prolonged illness is associated with an immune dysregulation which leaves traces in the blood, which could facilitate its detection and help provide a response to patients. Franceinfo summarizes what to remember from this study.

A component of the immune system that is disrupted

The work of this Swiss team is based on analyzes of blood serum, that is to say the liquid part of the blood, purged of its cells and proteins participating in its coagulation. The researchers examined the proteins present in the serum of 152 people, 113 of whom were infected with Covid-19. After six months, 40 of the patients showed symptoms of long Covid.

In the serum of the latter, scientists observed a modification of proteins linked to the complement system, which participates in the immune reaction and helps our body fight against infections. “In patients with long Covid, the complement system does not return to the resting state as it should”, but remains alert, explained the head of the study, Onur Boyman, to the Swiss press agency Keystone-ATS, cited by the Swiss daily The weather.

A possible explanation for the diversity of symptoms

The anomaly observed by the researchers is not without consequences: “If the complement system remains activated, it attacks healthy cells in different organs and damages or destroys them”explains researcher Onur Boyman, who is also director of the immunology clinic at the University Hospital Zurich.

“We have found another piece of the long Covid puzzle, which also explains why this disease can cause such varied symptoms”, estimates the scientist. It manifests itself as well as fatigue as cognitive disorders, attention or memory. “Patients talk about brain fog”reported to franceinfo Eric Guedj, head of the biophysics and nuclear medicine department of Marseille university hospitals. “Heart problems are also possible”he adds.

Avenues for screening and treatment, which still need to be tested

Currently, identifying long Covid is complicated. Symptoms can be confused with those of other illnesses. The definition adopted by the World Health Organization highlights this difficulty, because it attributes to long Covid any symptom that appears within three months following contamination, which lasts at least two months and has no other explanation. A finding by default, due to lack of a specific marker for this disease.

If confirmed, the results of the study by researchers at the University of Zurich would suggest a more reliable way to recognize the disease and distinguish it from other pathologies. However, screening does not appear to be easy, because the scientists used a complex method, which cannot be used on a daily basis in hospitals or laboratories, acknowledges Onur Boyman to Keystone-ATS.

Observations from this new study could also point the way to a treatment. The Swiss researcher notes that“there are already companies developing complement inhibitors”, drugs that attenuate the action of this component of the immune system, already used to treat other autoimmune diseases. But the study does not decide on their potential effectiveness against long Covid.

Other researchers, who were not involved in this study, call for caution and patience. Professor David Lynn, an immune system specialist at Flinders University (Australia), emphasizes that other recent work has highlighted the role of the complement system. “Much work still needs to be done to understand the different mechanisms that have been put forward in these different studies, and more importantly, to develop new treatments based on these findings,” he warns, cited by the Science Media Center.

This same source also reports the words of Peter Openshaw, professor of experimental medicine at Imperial College London: “It is important to emphasize that it would be premature to give new treatments to patients based on these findings, but the study shows how new therapies could be tested in future trials (some of which are already underway). ).”